Active Gust Load Alleviation by Means of Steady and Dynamic Trailing and Leading Edge Flap Deflections at Transonic Speeds

Abstract

Gust loads encountered during cruise flight induce critical loads to the aircraft structure. In this work the aerodynamic potential of different multifunctional Active Gust Load Alleviation (AGLA) concepts is assessed with the purpose to significantly reduce transient gust loads. The numerical investigations are conducted by employing a generic wing-fuselage aircraft configuration and RANS based CFD simulations. Idealized discrete "1-cos" type vertical gusts which are relevant for the certification process are used as representative atmospheric disturbances. Spanwise segmented trailing edge flaps and leading edge flaps are selected as promising gust load mitigation concepts. The first AGLA concept comprises steady flap deflections for load redistribution toward the wing root and the second concept utilizes dynamic flaps with time dependent deflection during the gust encounter. The final set of simulations combines both concepts. It is shown that steady flap deflection limit the reduction of maximum gust induced wing bending and wing torsional moments to 54% and 58%, respectively. A nearly full control authority over the gust loads represented by the wing bending moment and the wing torsional moment is achieved by a combination of steady flap deflections superimposed with dynamic flaps.